Run-Time Error and UserForms
 

I have a macro with about 20 userforms. As far as I can tell, it worked
great in Excel 2000 & 2002. I am now using the macro on a new machine with
Excel 2007. After I call the same sub-routine a bunch of times, I get:

Run-time error '75': Could not find specified object.

The debugger highlights "Load UserForm13", which I can see is right there in
VB interface and it just accessed it 3-20 times prior to failing. There is a
lot of other code, so I haven't bothered to provide this. Right now I am
operating in the mode of saving every action I take and then recovering when
Excel crashes. Any help or guidance would greatly be appreciated. Thank you
in advance.